add white list for NamePrefixBlacklist

[Hanmac]

i found after running rubocop on some of my gist files that it does have problems with defining "is_a?"
https://gist.github.com/Hanmac/4619845

  def is_a?(klass)
    super || __getobj__.is_a?(klass)
  end

[bbatsov]

Yeah, this makes sense. Something like this would be useful for AccessorMethodName as well.

[alexdowad]

Just opening a PR with NameWhitelist. @bbatsov, I can add the same for AccessorMethodName... but what will be on the default whitelist??

[Hanmac]

i don't know if its possible but i think there should be a whitelist check for all methods which are defined in parent classes/modules in case of overloading/overwriting of them (and the should be already reported in the parent class if they are part of the project too)

[alexdowad]

Hmm, interesting idea. @bbatsov @jonas054 @rrosenblum What do you think of automatically whitelisting predicate methods which are known to exist in a parent class/module?

[bbatsov]

What do you think of automatically whitelisting predicate methods which are known to exist in a parent class/module?

This will be extremely hard to track down with our current approach which doesn't keep track of any file state. After all, the parent classes will likely be in other files.

[bbatsov]

I can add the same for AccessorMethodName... but what will be on the default whitelist??

It can be just empty. I have the feeling many people would put get_ there. Anyways, I won't lose any sleep if we don't add this to RuboCop.